Unexpected response on /v2/example/errorwithdetails

[isbang]

🐛 Bug Report

When I run the example /v2/example/errorwithdetails, I got an unexpected message below.

{
  "code": 13,
  "message": "failed to marshal error message"
}

To Reproduce

1. Setup Docker

docker run -it -p 8080:8080 golang:1.15 /bin/bash

2. Setup environment inside of docker

apt-get update && apt-get install npm -y && npm install -g gulp-cli
GO111MODULE=on go get github.com/grpc-ecosystem/grpc-gateway/v2
cd /go/pkg/mod/github.com/grpc-ecosystem/grpc-gateway/v2@v2.0.1/examples/internal/browser
npm install && gulp bower && gulp backends

3. Test example outside of the docker

curl -X GET --header 'Accept: application/json' 'http://localhost:8080/v2/example/errorwithdetails'

Expected behavior

Response message below

{
  "code": 2,
  "message": "with details",
  "details": [
    {
      "stackEntries": [
        "foo:1"
      ],
      "detail": "error debug details"
    }
  ]
}

grpc-gateway/examples/internal/server/a_bit_of_everything.go

Lines 310 to 320 in 865774a

	func (s *_ABitOfEverythingServer) ErrorWithDetails(ctx context.Context, msg *emptypb.Empty) (*emptypb.Empty, error) {
	stat, err := status.New(codes.Unknown, "with details").
	WithDetails(&errdetails.DebugInfo{
	StackEntries: []string{"foo:1"},
	Detail: "error debug details",
	})
	if err != nil {
	return nil, status.Errorf(codes.Internal, "unexpected error adding details: %s", err)
	}
	return nil, stat.Err()
	}

Actual Behavior

Response message bellow with status code 500

{
  "code": 13,
  "message": "failed to marshal error message"
}

Your Environment

Mac os Catalina v10.15.7
Docker version 19.03.13, build 4484c46d9d
Image golang:1.15

[johanbrandhorst]

TIL we have a gulpfile in the depths of the examples 😆. Thanks for digging this up. I expect this is happening because the grpc-gateway server defined in https://github.com/grpc-ecosystem/grpc-gateway/tree/master/examples/internal/gateway doesn't have a way to understand the error details defined in the message returned from the gRPC server. It needs to import google.golang.org/genproto/googleapis/rpc/errdetails in order to be able to translate these messages from protobuf to JSON.

Would you like to contribute this fix and confirm it works?

[isbang]

I am not sure if I can fix this but I hope to try. May I try this?

In my opinion, main.opts from grpc-gateway/examples/internal/cmd/example-gateway-server/main.go#L26 needs Mux contains ErrorHandlerFunc to translate errdetails message. How do you think?

It needs to import google.golang.org/genproto/googleapis/rpc/errdetails in order to be able to translate these messages from protobuf to JSON.

I understood too late about this. Let me do this. 😄